Buyer Of My Used Car Wants To Sue Me For Mis-representing My Car

Location: New York, Maine

A couple of months ago I, the seller, resident of New York sold my pride and joy, a 1998 BMW classic car, to the buyer, resident of Maine. We completed the sale through the online auction house BringATrailer, a very popular and highly reputed auction vendor in the classic car community. I posted over 100 detailed pictures of the car and also posted my receipts and ledger of all the repairs and maintenance I've done to my car in my ownership. I also posted videos of the car driving, the top operation (it's a convertible) and a cold start video, all demonstrating that the car is in perfect working order. It was also inspected by the state of New York a couple of months prior and passed inspection. I also drove to the car up until the sale. Over a dozen people bid on the car but it was won by someone in Maine.

Fast forward to a couple of days ago and the new owner, with whom had very friendly conversations up until the car was picked up, sends me an email through his lawyer stating that he is going to sue me if I don't pay for $6k in repairs or buy the car back for the purchase price of $15k. He says that the I lied about all the mechanical repairs I did based on the fact that they didn't show up in his mechanic's database. All the parts he mentioned that I lied about all have date codes from the past 2 years, not to mention I have the receipts for them and evidence that I did them. I responded back with detailed information and evidence for each of the points he said I lied about. I also said I never stated in the listing that the work was done in a shop. Just because the work wasn't done in a shop doesn't mean it wasn't done. Any competent mechanic can tell that all the parts he mentioned are brand new on a car from 1998 !! Not to mention the car runs, drives, and stops perfectly fine.

Today he sent me an email seemingly defeated on trying to accuse me for mechanical faults and he has moved on to the interior. He stated very minor quirks and issues like the seatbelt guide not working and the pedal covers not being original. Most of these issues I did not even know about. Again, he is saying I have to either pay him or he will sue me because in Maine even though used cars are sold as is he can get me from mis-representing the car, which I did not do. I advertised the car to the best of my ability, and did mention the little issues in the car that I was aware of. It is a 27 year old car and he is expecting me to pay for repairs. The repairs are for things that I never worked on in the car but are wear and tear and maintenance items that need to be done on cars, especially luxury cars, every so often. He also got the invoice from a shop who will of course sometimes quote things that aren't completely necessary. What do I do ?